Rotor of a synchronous non-salient-pole machine

ABSTRACT

A rotor of a synchronous non-salient-pole machine has field winding coils placed concentrically relative to high teeth into alternate slots of different depth, the coils disposed in relatively deep slots are divided in height into two parts, and the front portions of the lower parts of the coils disposed in deep slots nearer to a high tooth are under the front portions of the coils disposed in slots further away from the high tooth so that the diameter of the rotor shaft is made greater at the place of the shifted portions of the coils.

United States Patent Obukhov et al. [4 1 July 31, 1973 [54] ROTOR OF A SYNCHRONOUS 1,361,546 12/1920 Politowski 310/187 X NQN SALIENT POLE MACHINE 3,408,516 /1968 Kudlacik 310/265 X 1,581,828 4/1926 Bergman 310/262 lnvemorsr VItaly Arsemevich Obukhov, Ulltsa 681,295 8/1901 Blood 310/265 Suvarova, 34, kv. 15; Vladimir Petrovich Glazkov, Ulitsa Festivalnaya, 16, kv. 2, both of Primary ExaminerJ. V. Truhe Lysieva, U.S.S.R. Assistant Examiner-B. A. Reynolds Filed: Jan. 25 1971 Attorney-Waters, Roditi, Schwartz & Nissen [21] Appl. N0.: 109,571

Related U.S. Application Data 57 ABSTRACT [63] Continuation of Ser. No. 789,489, Jan. 7, 1969,

abandoned- A rotor of a synchronous non-salient-pole machine has field winding coils placed concentrically relative to U.S. Cl. teeth into alternate slots of different depth, [he [51] 111'. CI. 02k 1/22 coils disposed in relatively deep SlOtS are divided in [58] Field of Search ..3l0/l87-189, 193, height into two parts, and the f t portions f the 1 207, lower parts of the coils disposed in deep slots nearer to 6 271 a high tooth are under the front portions of the coils disposed in slots further away from the high tooth so that the diameter of the rotor shaft is made greater at [56] References Cited the place of the shifted portions of the coils.

UNlTED STATES PATENTS 2,712,085 6/1955 Willyoung 310/262 X 7 Claims, 6 Drawing Figures /6 2/ /5 l9 l4 l7 /3 thebase of. the teeth formed by the slots. T he provision of projection 9 dictates a change in the shape of the coils placed in the rotor slots. In fact, in theabsence of the projection'9the front or end portions of the rotor coilsfwould be' shaped as shown in FIG. 3, with deep coils 10, 11 and 12 placed in theslotsl, 3 and 4, and shallow coils 13,14, 15 and 16, in the slots 5, 6, 7 and 8. With the projection 9 provided in accordance with centrically relative to the axis of the rotor.'The alternation order of the field winding coils'in' the front or end portion of such rotors is similar to that in the middle portion of the rotor. The disadvantages of such'machines are the great dimensions of their rotors for a given output power and inefficient use of the machine volume.

Accordingly, it is an object of the present invention 1 to overcome the disadvantages associated with the foregoing types of devices.

With these and other objects in view, theinvention contemplates reducing the magnetic induction at the root of the teeth formed bythe dots and in the rotor .yoke for obtaining higher output'powerwithout any change in overall dimensions of the machine. 7,

This objective is achieved by providing a rotor of synchronous non-salient-pole machine in which the field winding coils are into alternate slots of different depth, and wherein, according to the invention, the coils placed in deepslots are divided in the height into two parts, i.e. upper and lower parts, and the front portions of the lower parts are axially extended with respect to the upper parts and are disposed under the front portions of the coils in in narrow slots which results in an increased rotor shaft diameter at the location of the axial offset of the coils in the deep slots. This increase of rotor shaft diameter at the location of the offset'portions of the coils, that is, in themost saturated part of the rotor (at the root of the teeth) yields reduction of magnetic induction in the lower portion of the teeth and in the rotor yoke. As a result, a smaller magnetomotive force is required for passing the magnetic flux through the rotor.

The description of an illustrative embodiment of the present invention will now proceed in a more detailed explanation taken along with the annexed drawings, in which:

FIG. 1 is a cross-sectional view of a portion of an electric machine rotor with variable depth slots;

FIG. 2 is a section taken along line 2-2 in FIG. 1;

the present "invention, the front or end portions of the rotor coils are shaped as shown in FIG. 4, the shallow coils 13, I4, 15, and 16 being placed in slots of smaller depth as in FIG. 3, whereas the coils 10, 11 and 12 are replaced by coils which are divided vertically into two parts: namely coil 10 is divided into outer coil part 17 and inner coil part 18; coil 11 into outer coil part 19 and inner coil part 20, and coil 12 into outer coil part 21and inner coil part 22, the coil parts 17, 19 and 21 having the same height as the coils l3, 14, 15 and 16.

The front portions of the coils parts 18, 20 and 22 are located under the coils '15 21 and 16 which are arranged at the greatest distance from the rotor center,

' reckoned in the axial direction, to provide room for loeating the projection 9.

FIGS. 5 and6show the coil 10 divided into coil parts 17 and 18. These coilsare divided in their front portions only, the remainder being placed in the slots 2. I

The coils 1'1 and 12 are divided in a similar way.

' As aresultof'the above construction the teeth and the rotor yoke have a greater axial length in the most saturated part, that is, at the root of the teeth, which provides reduction of magnetic induction in the lower portion of the teeth and in the rotor yoke; This feature isparticularly effective for rotors with highly saturated lower parts of the teeth, a considerable saving of mate-. rials for the rotor windings being ensured due-to reduction of the magnetomotive force required for passing the magnetic flux through the rotor.

Finally, a higher output power can be obtained with the same overall dimensions of themachineand vice versa, with the same output power the overall dimensions of the machine can be reduced. Higher rigidity of the rotor can be considered as an additional improvement.

We claim:

1. A rotorfor a synchronous non-salient-pole man ately varying in depth to constitute shallow and deep FIG. 3 is a longitudinal sectional view through-a conslots, said coils being constituted deep coils located in the deep slots and shallow coils located in the shallow slots, said body including an end portion having an annular cavity into which said slots open, said coils including end portions which extend axially from said slots into said annular cavity, said rotor body including an annular projection extending axially into said annular cavity, the end portions of said shallow coils being staggered in length axially and being at a level surgitudinal section taken along the core. The core has slots 2, 3 and 4 which alternate with andare deeper than slots 5, 6, 7 and '8. The core 1 has an annular cavity as viewed in FIG. 2 with a cylindrical projection 9' which makes it possible to increase the diameter of the rotor core in the most saturated (magnetically) part, at

rounding said projection, the end portions of said deep coils including inner and outer coil parts axially offset in length from one another, the outer parts being at the same level as said shallow coils, theinner parts extending axially beyond said projection and below the level of the shallow coils and outer parts.

coil part has an axial length equal to the axial length of one shallow coil.

6. A rotor as claimed in claim 5, wherein a second inner coil part has an axial length equal to the ,axial lengthof a second shallow coil.

7. A rotor as claimed in claim 6, wherein a third inner coil part has an axial length equal to the axial length of one outer coil part in a different deep slot.

' t I! l i t 

1. A rotor for a synchronous non-salient-pole machine comprising a rotor body having a plurality of radial slots arranged in circumferential array around said body and extending axially along said body, and a plurality of coils seated in respective slots, said slots alternately varying in depth to constitute shallow and deep slots, said coils being constituted deep coils located in the deep slots and shallow coils located in the shallow slots, said body including an end portion having an annular cavity into which said slots open, said coils including end portions which extend axially from said slots into said annular cavity, said rotor body including an annular projection extending axially into said annular cavity, the end portions of said shallow coils being staggered in length axially and being at a level surrounding said projection, the end portions of said deep coils including inner and outer coil parts axially offset in length from one another, the outer parts being at the same level as said shallow coils, the inner parts extending axially beyond said projection and below the level of the shallow coils and outer parts.
 2. A rotor as claimed in claim 1, wherein each of said shallow coils has an axial length differing from each said outer coil part in said deep slots.
 3. A rotor as claimed in claim 2, wherein said shallow coils and outer coil parts have successively greater axial lengths.
 4. A rotor as claimed in claim 3, wherein said inner coil parts successively increase in projection from said slots.
 5. A rotor as claimed in claim 4, wherein one inner coil part has an axial length equal to the axial length of one shallow coil.
 6. A rotor as claimed in claim 5, wherein a second inner coil part has an axial length equal to the axial length of a second shallow coil.
 7. A rotor as claimed in claim 6, wherein a third inner coil part has an axial length equal to the axial length of one outer coil part in a different deep slot. 